1. Field of the Invention
The present invention relates in general to data processing systems and, in particular, to a data processing system and method for prohibiting access to a SCSI bus. Still more particularly, the present invention relates to a data processing system and method for prohibiting external devices from accessing a SCSI bus prior to a correct entry of an access password.
2. Description of the Related Art
Personal computer systems are well known in the art. They have attained widespread use for providing computer power to many segments of today""s modern society. Personal computers (PCs) may be defined as a desktop, floor standing, or portable microcomputer that includes a system unit having a central processing unit (CPU) and associated volatile and non-volatile memory, including random access memory (RAM) and basic input/output system read only memory (BIOS ROM), a system monitor, a keyboard, one or more flexible diskette drives, a CD-ROM drive, a fixed disk storage drive (also known as a xe2x80x9chard drivexe2x80x9d), and a pointing device such as a mouse. One of the distinguishing characteristics of these systems is the use of a motherboard or system planar to electrically connect these components together. Examples of such personal computer systems are IBM""s PC 300 series, Aptiva series, and Intellistation series.
Storage systems may be coupled to computer systems utilizing a variety of communication protocols or standards. One such standard is the small computer system interface, or SCSI. The SCSI standard defines a particular command set which provides an interface between a computer system and peripherals.
A SCSI bus carries data and control signal lines from a SCSI controller to and from the SCSI devices coupled to the bus. One SCSI bus signal line is a BUSY signal line. The BUSY signal line is utilized to indicate when the SCSI bus is busy. When the BUSY signal line is asserted, neither devices nor controllers may utilize or gain control of the SCSI bus. When the BUSY signal line is asserted, it is held at a logical LOW to indicate that the line is busy. When the BUSY signal line is de-asserted, the line is pulled high to indicated that the line is not busy. Any device may assert the BUSY signal line. Only the system planar, however, may de-assert the line.
A SCSI bus, internal within a computer system, may be accessed both by the computer system""s internal devices and processor, as well as external devices including an external processor utilizing an external connector. The internal SCSI bus devices are not secure in a system having an external connector. As long as the internal SCSI bus devices are receiving power, they may be accessed by an external controller utilizing the external connector. The external controller could access, change, or destroy data stored within the internal devices.
Therefore a need exists for a data processing system and method for prohibiting devices from accessing a SCSI bus prior to an entry of a valid password.
A data processing system and method are disclosed for prohibiting access to a SCSI bus prior to a correct entry of an access password. The system includes a plurality of internal SCSI bus devices coupled to the SCSI bus. The system also includes an external SCSI connector for coupling external SCSI devices to the SCSI bus. The access password is established and stored within the system. The plurality of internal SCSI bus devices and the external devices are prohibited from accessing the SCSI bus prior to a correct entry of the access password. The SCSI bus includes a busy signal line. Prior to a correct entry of the access password, the system asserts the busy signal line, indicating that the SCSI bus is busy. Both internal and external devices are prohibited from accessing the SCSI bus while the busy signal line is asserted.
The above as well as additional objectives, features, and advantages of the present invention will become apparent in the following detailed written description.